Lecture 4: White blood cells

Question 1

What is thrombocytopaenia?

Answer 1

Low platelet count

Question 2

What are the phagocytes?

Answer 2

Granulocytes (neutrophils, eosinophils, basophils) and Monocytes

Question 3

Write some notes on neutrophils

Answer 3

• Dense nucleus with 2-5 lobes
• Granules in cytoplasm
• Beyond five lobes is an indicator of age

Question 4

How are neutrophils measured?

Answer 4

In absolute values

Question 5

What are neutrophil precursors?

Answer 5

Myeloblasts and these come from MSC and HSC

Question 6

Describe the granulocyte growth kinetics?

Answer 6

• 7-10 days maturation in bone marrow
• Theres a range of precursors & the presence if banded nucleus indicates inflam and early release
• Circulate only for 6-10hrs

Question 7

What is neutropenia?

Answer 7

Low granulocyte count and they cant be transfused

v at risk of infection

Question 8

What regulates granulopoiesis?

Answer 8

Heamopoetic growth factors

-> IL3, stem cell factor, GM-CSF, G-CSF

RELEVANT GROWTH FACTORS AND MICROENVIRONMENT

NB: G-CSF in clinical use in NZ

Question 9

What are the functions of neutrophils?

Answer 9

1. Chemotaxis
2. Phagocytosis
3. Killing of bacteria: Oxidative and non-oxidative

Question 10

What is neutrophil leucocytosis:

Answer 10

• Feature of infection and inflammation i.e bacterial infection (examined for in appendicitis)
• May be associated with left shift i.e more immature forms of blood cells i.e banded neutrophils

Question 11

Describe histological appearance of monocytes:

Answer 11

• Central oval or indented nuclei

- Blue-grey cytoplasm with granules

Question 12

Describe monocyte development:

Answer 12

Monoblast -> Promonocyte -> Monocyte

Share common precursor with neutrophil (Myeloblast)

Question 13

Describe monocyte kinetics:

Answer 13

• Circulate for 1-3 days
• Enter tissues and transform into macrophages
• Related cells throughout body; Kupffer cells, alveolar macrophages, langerhan cells, microglial cells brain

Question 14

What are the functions of monocytes/macropahges:

Answer 14

Phagocytosis

Synthetic function

Antigen presentation

Question 15

What types of infections do monocytes/macrophages fight? and what are their methods?

Answer 15

Phagocytic cells:
- Chronic infections, intracellular parasites i.e TB

• > Chemotaxis
• > Opsonisation
• > Phagocytosis and ingestion
• > Killing of ingested bacteria by fusion with monocytic lysosomal granules

Question 16

What is the synthetic function of macrophages/monocytes:

Answer 16

Synthetic function:

• Complement
• Interferon
• Cytokines i.e TNF, IL1, Growth factors
• Prostaglandins

Question 17

What is monocytosis and its clinical picture:

Answer 17

Monocytosis: (increased count)

• Reactive in origin: Chronic infections i.e TB, Osteomyeltiis
• Malignant: Acute myeloid leukaemia (monoblastic sub type), Chronic myeloid leukemia (absent of underlying illness of course)

Question 18

Describe the histological appearance of eosinophils:

Answer 18

• Bilobed nucleus (fortune cookie)
• Red staining granules
• Very rare in blood

Question 19

What is eosinophilia?

Answer 19

Allergic or hypersenstivity reactions i.e hayfever, asthma, drug reactions

Parasetic infestations

Question 20

Describe basophils appearance under microscope and primary function:

Answer 20

Infrequent cells in blood

• Deep blue granules over the nucelus
• IgE binding sites (degranulation->histamine)
• Releated to mast cells

Question 21

What is the function of basophils?

Answer 21

• Close relationship to mast cells
• Granules-> Histamine
• Type 1 hypersenstivity reaction

Question 22

When are basophils high?

Answer 22

Probably in neoplastic syndromes, not hypersensitivity reactions

Question 23

Whats the histological appearance of lymphocytes?

Answer 23

• Condensed chromatin nuclei
• Thin rim of agranular cytoplasm
• Cant distinguish B from T

Question 24

What are the proportions of circulating lymphocytes?

Answer 24

Circulating lymphocytes:

• 65-80% T cells
• 5-15% B cells
• NK cells (Larger cytplasmic granules)

Question 25

What are the primary lymphoid organs?

Answer 25

B cells = bone marrow

T cells = Thymus

Question 26

IF the spleen is palpable whats the implication?

Answer 26

It has doubled in size

Question 27

Whats of note with lymph node enlargement?

Answer 27

Reactive: Viral infection, local bacterial infection (short lived, tender)

Malignant: Lymphoma or metastatic spread (often isolated nodes, no tender, not resolving)

Question 28

What is lymphocytosis?

Answer 28

Reactive i.e viral infections i.e infectious mononucleosis

Malignant i.e CLL

Question 29

What can cause lymphopenia?

Answer 29

HIV infection: CD4 pos T cells
-> Profound T cell deficit, opportunistic infections, malignancies

Others: Congenital immune defects, steroid therapy, severe bone marrow failure